NATICK, Mass -- Boston Scientific Corp. surprised investors by naming James R. Tobin, who oversaw the growth of Biogen Inc. into one of the world's biggest biotechnology companies, as its president and chief executive officer.

Wall Street was elated, both because Mr. Tobin is highly regarded and because his decision to join Boston Scientific is viewed as a vote of confidence in the company's future after a rocky 1998. Shares of the...